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CP Monitors
Pipeline operators must confirm that pipelines and other buried metal structures such as tanks and vessels, are protected cathodically against corrosion. This can be done in various ways:
In impressed current systems
• By taking pipe-to-soil potential measurements at test posts along the pipe (usually sited at road, rail and river crossings and at field/property boundaries and other rights of way).
• By checking sleeves, critical bonds and isolation joints to make sure that the integrity of the pipeline is maintained.
In galvanic systems
• By checking the supply of current from the sacrificial anode to the structure it is protecting
Although not usually taken as frequently as at the rectifier, measurements at CP test points are only spot checks. Again, they only indicate problems well after they have occurred and have no alarm capability
By contrast, MERLIN CP Monitors provide an immediate indication of CP levels at the important points in the pipeline network. In a well maintained CP system all points should be tested periodically but “key posts” should be monitored more intensively, including:
• Mid-points, end points and low points on impressed current pipelines
• Points where pipelines cross and may interfere with each other’s protection
• Bonds, linking pipelines in a common corridor so that they are both protected equally
• Isolation joints, ensuring that buried (CP-protected) and above-ground (earthed) structures are electrically disconnected from each other
• Areas where pipelines are affected by electromagnetic fields from power conduits such as buried or overhead high voltage cables
• Points that are difficult to access, either physically (terrain) or for other reasons, such as on private land where permission is required
• Points in hazardous areas or situated at busy roadsides
• Downstream of compressor stations, where elevated gas temperatures may accelerate the corrosion process.
Two types of CP monitor are available:
• MERLIN CP Monitor is a small, battery-powered unit that can be housed within a suitably sized test post or within a bond box.
• MERLIN CP Hemi Monitor is a hemi-cylindrical monitor packaged to fit invisibly within a standard diameter cylindrical riser.
Both monitors check voltage and current levels (both DC and AC) and alarm immediately if a value exceeds a user-preset user threshold. They have two voltage inputs so that, if a coupon is installed at the test point, they can take instant OFF and current measurements. Alternatively the two inputs can be used for ON potential measurements on adjacent pipelines, or either side of an IJ. A current channel input allows coupon or bond currents to be monitored.
These monitors communicate using the GSM network. Data is automatically stored and transmitted in a management report to the system HQ where it is displayed and archived in the MERLIN CPSM3 software or accessed on-line via iCPSM.
There are many other benefits:
User Alerts
User-settable high and low alarm thresholds for all measurement channels.
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Custom Reports
Data automatically archived and presented in regulatory reporting format.
Environmental
Eliminates the impact of emissions from survey vehicles, saves thousands of driving miles per month, zero carbon footprint.
GSM (SMS) Communications
Installation, configuration and control of monitors via the most cost efficient communication method.
Health and Safety
No risk assessments or lone worker issues at remote or difficult to access sites. Protects technicians from exposure to voltages and currents.
Cost Reduction
Achieves rapid financial payback on the huge cost of taking frequent manual measurements.
For further details and to view the full product specification see the links on the left side menu for more information.